The present invention relates to cargo carrying containers suitable for use in multi-mode transportation of freight or cargo by ship, rail, or overland truck. Examples of intermodal cargo containers are found in U.S. Pat. Nos. 3,085,707; 3,646,609; 4,212,405; 4,844,672; and, 5,205,428.
Intermodal cargo containers generally are constructed to certain standard dimensions and have structural features that minimize handling problems and allow for the stacking of containers, particularly when used in a ship or rail mode. Certain changes in overall width, length and height have been adopted from time-to-time for certain newer style containers, but such changes in overall dimension have only been made in such a manner to accommodate stacking arrangements with older style containers. For example, the intermodal containers constructed as disclosed in U.S. Pat. No. 3,085,707 were built at a standard length of 40 feet. The containers of U.S. Pat. No. 3,646,609 were intended to be longer than 40 feet in length, but were fitted on top and bottom with an intermediate set of castings which are connected together with a structural frame to allow the longer containers to be stacked and lifted at these intermediate points. The required thickness of the floor of the container necessary to bear the load is generally sufficient to enclose the castings which are employed on the bottom of the container for stacking purposes. On the other hand, the intermediate castings which are situated at the top of the containers as disclosed in U.S. Pat. No. 3,646,609 are considerably larger than either the thickness of the wall or roof and thus intrude into the cargo area of the container. This intrusion into the cargo area of the intermediate top castings has many disadvantages, and attempts have been made to reduce or eliminate this intrusion.
Certain newer containers which have sought to maximize the inside height, such as that disclosed in U.S. Pat. No. 5,205,428, have avoided this intrusion by eliminating the intermediate top casting which would permit stacking and replaced it with a side lift design intended to interact with either pin or wedge type handling devices. Such handling devices still maintain the existing lifting locations at the 40 foot apart intermediate lift points of the containers, but do not permit stacking at these locations. As such, these units can generally only be included in a stack of containers as the top unit thus reducing the flexibility of the unit and creating certain logistics problems for operators of intermodal container terminals.
One means of solving this problem is to create a stacking frame at each extreme end of the container and install conventional stacking castings to allow interlocking of the units together using conventional interbox connectors. However, when this is done, the stacking castings again intrude into the top of the cargo area at the front and rear corners. Such intrusion has the effect of reducing the usable inside length of such a container by as much as 12 inches which is not desirable. The present invention is an alternative solution which avoids any substantial intrusion into the enclosed cargo area while at the same time permitting the container to be situated at any point in a stack of longer containers.